Modular applicator system

ABSTRACT

A fluid operated system of modular guns for extruding or spraying liquids such as molten adhesives. The system includes multiple guns in the form of readily removable cylindrical modules that mount in apertures of a fixed service block or manifold which receives the supply lines for the liquid and the gun operating pressurized fluid. The service block and guns have passages which register when the system is assembled whereby the guns may be easily removed from the fixed service block and replaced without disconnecting any fluid lines or other service equipment.

United States Patent Baker et a]. 51 Sept. 12, 1972 1 MODULAR APPLICATOR SYSTEM 3,332,581 7/1967 Estabrooks ..222/504 [72] lnventors: Robert G. Baker, Avon; Samuel R.

Pnmary Examiner-Stanley l-l. Tollberg Row! Lorain both of Ohm Atl0rney-Wood, l-lerron & Evans [73] Assignee: Nordson Corporation, Amherst,

Ohio [57] ABSTRACT [22] Filed: Nov. 13, 19 70 A fluid operated system of modular guns for extruding or spraying liquids such as molten adhesives. The [2]] Appl 89381 system includes multiple guns in the form of readily Related Application D: removable cylindrical modules that mount in apertures of a fixed service block or manifold which comlmlatlon-m-pm 0f 775J77, receives the supply lines for the liquid and the gun 70,72S. operating pressurized fluid. The service block and guns have passages which register when the system is [52] U.S. Cl ..222/504 assembled whereby the guns may be easily removed [51] Int. Cl. ..G0lf 11/06 from the fixed service block and replaced without [58] Field of Search ..222/275, 504, 510, 330, I32 disconnecting any fluid lines or other service equipment. [56] References Cited UNITED STATES PATENTS 27 Claims, 3 Drawing Figures 3,094,254 6/1963 Cullen et a]. ..222l504 MODULAR APPLICATOR SYSTEM This application is a continuation-in-part application of our copending application Ser. No. 776,177 filed Nov. 15, 1968, now US. Pat. No. 3,570,725 entitled Modular Adhesive Applicator, which application is assigned to the assignee of this application.

This invention relates to the application of liquids to surfaces and especially to equipment used to apply beads, ribbons or small unitary deposits of extruded or sprayed material in a desired pattern under high speed production conditions. More particularly, the invention relates to equipment which is particularly suitable for applying heated liquids such as hot melt molten adhesives to various materials such as flat sheets or webs of paper or cardboard of the type commonly used in packaging and adhering a variety of products. The invention, though, is equally applicable to the application of other liquid materials such as coating materials and paints which may be applied cold or at room temperature.

Hot melt liquids are typically of the asphaltic or synthetic resin type and are generally in their solid state at room temperature. When heated to molten form,

- however, they change in physical state to a relatively viscous liquid which may be pumped through the nozzle of an applicator tool or gun and applied to a surface in the form of a continuous bead or ribbon or as intermittent deposits. Normally, such hot melt materials are converted to a molten state in a heater and then transmitted to applicator guns under pressure through heated lengths of flexible hose. The applicator guns are preferably heated also to assure that the adhesive remains in molten form until it leaves the nozzles of the guns.

In many high speed packaging applications, the molten or liquid hot melt is applied to moving sheet material such as a web of paper or flattened cardboard cartons. In other applications the hot melt is applied to filled containers prior to the sealing of the flaps or an end closure. In still other applications, the molten material is used in the coating or assembly .of parts.

Certain types of applicator guns used for application of hot melt adhesives as well as the application of other liquids are operated'by means of fluid cylinders which open and close a valve in the molten liquid feed line and thus interrupt the extrusion or expulsion of the liquid from the nozzle of the gun. Where air operated guns are used it is necessary, of course, to use an air pressure line from a pressure source. Also, since the body of the gun is normally heated to maintain the liquid in a molten or low viscosity state, it is essential that electrical service lines also be connected to the gun.

A problem encountered with this type of equipment, particularly in the application of hot melt adhesive but also in the application of other liquid materials, has been the time consuming cleaning operation which must be accomplished at periodic intervals. The cleaning requires the removal of all of the fluid lines and other service lines from the gun and afterward the reconnection of the lines as well as the careful repositioning of the gun so as to extrude the beads of liquid at a proper predetermined location. All this is quite time consuming and requires the interruption of a continuous production facility at frequent intervals.

It has therefore been an objective of this invention to substantially reduce or eliminate the difiiculties encountered in cleaning or replacing applicator guns. v

Another objective of this invention has been to reduce the number of supply lines and service lines modular apparatus with a fluid or air type operatingv system and a pumping system for the viscous liquid to be extruded or sprayed, the apparatus including a fixed service module or manifold defining a passage or manifold for the viscous liquid and a passage or manifold for operating fluid. The passage for the viscous liquid communicates with the pumping system and the passage for operating fluid communicates with a fluid pressure line. One or-more removable gun modules are mounted in the fixed service block module. Each gun has a passage communicating between the viscous liquid passage in the service block module and an extrusion nozzle, and a passage for operating fluid communicating between the operating 7 fluid passage in the service block and a fluid cylinder.

The guns are cylindrical and have threads for mounting removed from the service module for service or replacement without disturbing the connections to the service module (air line, electrical lines and hydraulic lines.) Multiple guns may be mounted in the service module in a random pattern (not necessarily in a straight line or geometrical pattern, nor necessarily parallel to each other) so that a pattern of adhesive or other material can be applied to a product or a substrate to fulfill any pattern requirement. Each gun consists of a cylindrical body which contains a ball valve, located in a chamber which is filled with the viscous liquid when the gun is in operation. The valve is opened by a rod which is attached to the ball and passes through a seal which separates the liquid material from an atmospheric vent chamber. The rod continues through a second seal located between the vent chamber and an air cylinder where the rod is attached to a piston. By applying pressurized fluid, as for example air, to the piston the ball is pulled from the valve seat allowing material to flow out of the gun onto the product or substrate. When the pressure is removed from the piston a spring returns the ball to its closed position on the valve seat. An adjustment is provided on the return spring so that the amount of fluid pressure required to actuate the gun is adjustable. Since the force required to actuate each individual gun varies because of differing internal gun fiction forces, the adjustable preload of the spring allows several guns to be adjusted to equalize the pressure required to open each gun. Thus each gun may be adjusted to open at the same time. This is particularly desirable when the product or substrate is moving and registration of the pattern is required.

Inthe preferredembodiment a heater is provided in the service module to maintain the liquid in a molten or low viscosity state until after it leaves the nozzle of the gun.

The primary advantage of this modular applicator system is the ease with which it enables multiple modular guns to be arranged in random, closely spaced patterns. The patterns may have points of application spaced as closely as the diameter of a single gun and may be arrangedor configurated in any pattem' in which gun receiving holes may be drilled or machined into the service module or block.

Another advantage of this invention is the miniturization which it facilitates Guns constructed in accordance with this invention may be manufactured relatively inexpensively in small sizes or in small diameter cylindrical housings. These small size guns in turn may be used in applications where larger guns would not fit and could not be accommodated.

.These and other objects and advantages of this invention will be more readily apparent from the following description of the drawings in which:

' FIG. 1 is a cross sectional view through a modular system incorporating the invention of this application.

FIG. 2 is a cross sectional view through the service module taken on line 2-2 of FIG. 1.

' FIG. 3 is an enlarged cross sectional view through a gun module taken on line 33 of FIG. 1.

. Referring first to FIG. 1', there is illustrated a fourgun applicator system for-applying a heated liquid material to a substrate. In the illustrated embodiment the'four gun modules or guns 11', l2, l3 and 14 are mounted in alignment in a service module or service block 15. The guns could, though, be mounted out of alignment or in any pattern in the service module 15 but for ease of illustration they are shown in linear alignment.

' The servicemodule 15 comprises a generally rectangular block through which there extends a pressurized fluid or air passage 16 and a parallel liquid flow passage 17. In the preferred embodiment there is also an atmospheric vent passage 18 extending parallel to and located between the two other passages 16 and 17. These three transverse passages are intersected by four gun mounting apertures 20, 21, 22 and 23 which are perpendicular to the passages 16-18. The apertures 20- 23 are step bored for reception of the guns 11-14 respectively and each includes a small diameter end section 24, a larger diameter section 25, a still larger diameter middle section 26 and a large diameter end section 27. Aportion of the large diameter end section 27 is threaded, as indicated at 28, for reception of a threaded end section of a modular gun, as is explained more fully hereinafter.

' In applications in which the system is intended to be used to apply hot melt or heated materials, the service module or block 15 includes a transverse bore 30 within which there is mounted an electrical resistance heater 31. The flow of electrical current through this heater 3] is controlled by a thermostat 32 mounted in a recess 33 in the face of the block 15. The, recess is covered by a plate 34 bolted or otherwise secured to the service module so as to enclose the thermostat containing recess 33.

The service module may be mounted at an applicator station in any convenient manner. In the illustrated embodiment the service block 15 is secured to a mounting bracket 38 by bolts 39. The mounting bracket is in turn slideable over a bar 40 to which it is secured by a locking screw 41.

The four gun modules 1 1-14 are identical and therefore only one is illustrated and described in detail. As may be seen most clearly in FIGS. 1 and 3, the gun modules are generally circular and tubularin configuration for mounting in the circular cross section apertures 20-23 of the service module. Each gun includes a tubular body 45 through which there extends an axial bore 46. This bore defines a high pressure fluid or air cylinder 47'at one end and a liquid chamber 48 at the opposite end. A small diameter section 49 of the bore interconnects the cylinder 47 and chamber 48.

The bore 46 of the body is closed at one end by an end closure cap 50 threaded into an internally threaded end 51 of the bore 46. The opposite end of the bore 46 in the body 45 is similarly closed but by a nose piece 53 threaded into an internally threaded end section 54 of the body.

A stepped axial bore 55 extends through the nose piece 53. The larger diameter section of this bore 55 defines a chamber 56 which is open to the liquid chamber 48 of the body. This latter chamber 56 communicates with a small diameter port 57 which isopen to the end of the gun. In the illustrated embodiment, the nozzle 59 of the gun is threaded onto the end of the nose piece 53.

An internal shoulder of the nozzle 53 at the intersection of the small diameter bore 57 and the larger diameter chamber 56 forms a valve seat 63 for a ball valve 64. This ball valve 64 and valve seat 63 together form a check valve 65 for controlling flow of pressurized liquid from the liquid chambers 56 and 48 of the gun. Liquid is supplied to these chambers through a transverse passage 66 inthe body 45 of the gun. When the gun is assembled in the service module or service block 15, this passage 66 registers with the transverse liquid supply passage 17 through which liquid, as, for example, hot melted adhesive, is supplied to the system 10 at high pressure, as, for example, 400 pounds per square inch.

The ball valve 64 is mounted upon one end of a piston rod 68. This rod extends upwardly through the small diameter section 49 of the bore 46 and at the opposite end terminates in a threaded section 69. A piston 70 is mounted upon the threaded section 69 of the rod. This piston comprises four stacked rings 71-74. The upper one 74 and the lower one 71 of these rings are threaded onto the section 69 of the rod 68 so as to facilitate adjustment of the piston on the rod. This adjustment of the piston enables the stroke of the check valve to be adjusted by varying the distance the piston is movable from a valve closed position to a position in which the top 87 of the piston 70 contacts the bottom surface 88 of the closure cap 50.

An air seal, preferably a Teflon seal, is sandwiched between the two middle rings 72 and 73 of the piston. This seal 75 prevents the escape of air pressure from the high pressure cylinder 47 located beneath the piston to a low pressure chamber 76 in the closure cap 50. This latter chamber 76 is maintained at atmospheric pressure through a transverse passage 77 in the cap 50 which opens to atmosphere.

An'adjustable preload spring 80 is located in the chamber 76 of the closure cap and bears against one side of the piston 70 so as to force the piston and the ball valve 64 to a closed position. The opposite end of this spring 80 bears against an adjustable seat 81 which is slideable in the chamber 76 of the closure cap. This seat 81 rests against an end 82 of a preload adjustment screw 83. The screw is threaded through a threaded aperture 84 of the closure cap 50 and is secured in an adjusted position by a lock nut 85. By adjusting the screw 83 and thus the axial position of the seat 81, the force holding the valve closed and thus the force required to open the valve may be adjusted. This adjustment enables air pressure required to open several guns to be equalized even though the internal friction of the individual guns may be different.

Air pressure in cylinder 47 controls opening and closing of the check valve 65. This pressure, generally in the form of air pressure, is supplied to the cylinder 47 through a transverse passage 86 which registers with the passage 16 in the service module. High pressure air supplied to the passage 16 effects opening of the check valves by causing the pistons of the guns to move upwardly until the tops 87 of the pistons engage the bottom edge 88 of the caps 50. When the pressure in the passage 16 is released or opened to atmosphere, the springs 80 effect closing of the valves.

In order to prevent leakage of air pressure from the chamber 47 through the bore 49 and to prevent leakage of liquid from the chamber 48, an air seal 90 is provided around the rod 68 in the air cylinder 47 and a liquid seal 91 is provided around the rod 68 in the liquid chamber 48. The seal 90 includes a resilient Teflon washer 92 held in place by aspring washer 93. The liquid or hydraulic seal 91 also includes a resilient Teflon washer 94 but this seal is held in place by a washer 95 and a backing spring 96. At one end the spring bears against the washer 95 and at the opposite end it bears against an end surface 97 of the nozzle 53. To further insure that liquid does not leak into the air cylinder, a transverse vent aperture 98 is provided in the body 45 intermediate to the seals 90 and 91. This vent 98 is connected to the through passage 18 in the service module so that it is always open to atmosphere.

OPERATION The four guns 11-14 are individually threaded into the service module and when so assembled, the air passages 86 of the guns register the air passage 16 of the service module. Similarly, the liquid passages 66 register with the liquid passage 17 of the service module and the atmospheric vents 98 register with the atmospheric vent 18 of the service module. Air is prevented from leaking around the exterior of the gun from the passage 16 to the passage 18 by O-ring seals 100 which are mounted in grooves 101 in the exterior of the bodies 45. Two other O-rings 102 and 103 are mounted in grooves 104 and 105 in the bodies 45 to prevent liquid from leaking around the exterior of the body from the liquid passage 17 of the service module.

The individual guns are so adjusted by the preload adjustment screw 83 that all four open simultaneously when air pressure is supplied to the gun through the passage 16 of the service module. This air pressure causes the pistons of the guns to move upwardly until the top surfaces 87 of the pistons contact the bottom surfaces 88 of the closure caps 50. This upward movement of the pistons effects the upward movement of the check ball valves 65 and permits liquid supplied to the guns at high pressure (as, for example, 400 psi) in passage 17 to pass through and out of the liquid chambers 55 via the nozzle ports 57. The strokes of the guns are preadjusted prior to assembly of the guns by locating the pistons 70 on the piston rods 68 so that the liquid flows at the proper rate through the check valve 65. After the liquid material has been deposited upon a substrate, the air pressure in passage 16 is opened to atmosphere and the guns are caused to close as a result of the springs forcing the pistons and the attached check valves to a closed position.

When it is necessary to clean one of the guns or if foreign matter should cause a gun to break, the service lines to the service module 15 need not be disconnected from the service module. Specifically, the air line to the passage 16, the fluid line to the passage 17 and the electric lines to the heater 31 and thermostat 32 need not be disconnected. All that is required is for the lines to be closed or shut off and the clogged or broken gun to be removed by unthreading it from the mounting aperture of the service module. A new gun may then be inserted by threading it into the aperture and the system restarted. The clogged or broken gun may then be cleaned or repaired without closing down any production facilities while this cleaning or repair takes place.

While we have described only a single preferred embodiment of the invention, persons skilled in the art to which this invention pertains will readily appreciate changes and modifications which may be made without departing from the spirit of our invention. Specifically, the modular guns may be arranged in any kind of random pattern in a mounting block and may be angulated relative to each other so as to locate the deposits from the gun in even closer spacing than the spacing of the gun nozzle orifices. Additionally, the system has been specifically described as applied to a hot melt application and including a heated service module. The invention is equally applicable, though, to unheated liquid applications. Therefore, we do not intend to be limited except by the scope of the appended claims. Having described our invention, we claim:

1. A modular apparatus for emitting a liquid from a pressurized source onto a substrate comprising a service block module having essentially only static parts and defining a first passage for a liquid, and a second passage for a gun actuating pressurized fluid, said module having at least one aperture intersecting said passages,

a readily removable gun module including a body mounted in said aperture of said service block module,

said gun module including a nozzle,

said gun module including essentially all the movable parts of said apparatus, said gun module body defining a first passage for liquid communicating between said liquid passage in said service block module and said nozzle, said first passage in said gun module body being in sealing registration with said liquid passage in said service block module when said modules are in assembled relation, said gun module body also defining a second passage for pressurized fluid communicating between said pressurized fluid passage in said service block module, said pressurized fluid passages of said gun module and service module also being in sealing registration when said modules are in assembled relation,

movable valve element in said gun module for opening and closing liquid flow through said nozzle, and

' movable means in said gun module responsive to connection with said pressurized fluid for operating said valve.

2. The modular apparatus of claim 1 which further includes multiple apertures intersecting said service block module passages and a readily removable modular gun mounted in each of said apertures.

3. The modular apparatus of claim 1 in which said gun module body is generally cylindrical in configuration and in which said aperture is circular in cross section, said aperture having internal threads and said gun module body having external threads threaded into said threaded aperture so as to removably mount said gun module in said aperture.

4. The modular apparatus of claim 2 which further includes spring means for biasing each of said valve elements of each of said gun modules to a closed position and adjustable preload means for adjusting the spring tension operable to maintain said valve elements in a closed position, said adjustable preload means enabling the several gun modules to be adjusted to equalize the pressure required to open each gun module.

5. The modular apparatus of claim 4 which further includes means to adjust the stroke of each of the movable valve elements of each of the gun modules, said stroke adjustment means being independent of said preload adjustment means in each of said gun modules.

6. The modular apparatus of claim 1 in which the said gun module body is generally cylindrical body and has a through bore extending axially therethrough, a portion of said body being externally threaded so as to enable said body to be threaded into a threaded section of said aperture of said service block module, the axial bore of said cylindrical body being internally threaded at its opposite ends, said nozzle being threaded into said bore at one end and a closure cap threaded into the threaded bore at the opposite end.

7. The modular apparatus of claim 6 in which a portion of said axial bore defines a fluid cylinder in said gun module at one end of said cylindrical body and another portion of said axial bore defines a liquid chamber at the opposite end of said body, said first passage of said gun module communicating with said fluid cylinder and said second passage of said gun module-communicating with said liquid chamber.

8. The modular apparatus of claim 7 in which said movable means includes a piston slideable in said cylinder and which further includes spring means operable between said piston and said closure cap to bias said piston and said movable valve element to a closed position.

9. A modular apparatus for ejecting a liquid from a pressurized source onto a substrate, comprising a fixed service block module having essentially only static parts and defining a passage for liquid and a passage for pressurized operating fluid, said service block module having at least one aperture intersecting said passages,

a readily removable gun including a body removably mounted in said aperture of said service block module,

said gun module including a nozzle,

means defining a fluid cylinder in said gun module body,

a piston in said fluid cylinder,

said gun module body containing essentially all the movable parts of said apparatus and defining a first passage communicating between said liquid passage in said service block module and said nozzle and a second passage communicating between said fluid passage in said service block module and said fluid cylinder, said first and second passages of said body being in sealing registration with their respective passages in said service block module when said modules are in assembled relation, and

a movable valve element in said gun module operatively connected to said piston for opening and closing liquid flow through said nozzle.

10. The modular apparatus of claim 9 which further includes multiple apertures intersecting said service block passages and a readily removable modular gun mounted in each of said apertures.

11. The modular apparatus'of claim 9 in which said gun modules body is generally cylindrical in configuration and in which said aperture is circular in cross section, said aperture having internal threads and said gun module body having external threads threaded into said threaded aperture so as to removably mount said gun module body in said aperture.

12. The modular apparatus of claim 10 which further includes spring means for biasing each of said valve elements of each of said gun modules to a closed position and adjustable preload means for adjusting the spring tension operable to maintain said valve elements in a closed position, said adjustable preload means enabling the several gun modules to be adjusted to equalize the pressure required to open each gun module.

13. The modular apparatus of claim 12 which further includes means to adjust the stroke of each of the movable valve elements of each of the gun modules, said stroke adjustment .means being independent of said preload adjustment means in each of said gun modules.

14. The modular apparatus of claim 9 in which the said gun module body is generally cylindrical and has a through bore extending axially therethrough, a portion of said body being externally threaded so as to enable said body to be threaded into a threaded section of said aperture of said service block module, the axial bore of said cylindrical body being internally threaded at its opposite ends, said nozzle being threaded into said bore at one end and a closure cap threaded into the threaded bore at the opposite end.

15. The modular apparatus of claim 14 in which a portion of said axial bore defines said fluid cylinder in said gun module at one end of said cylindrical body and another portion of said axial bore defines. a liquid chamber at the opposite end of said body, said first passage of said gun module body communicating with said fluid cylinder and said second passage of said gun module body communicating with said liquid chamber.

16. The modular apparatus of claim which further includes spring means operable between said piston and said closure cap to bias said piston and said movable valve element to a closed position.

17. The modular apparatus of claim 16 which further includes adjustable preload means for adjusting the spring tension operable to maintain said valve element in a closed position.

18. The modular apparatus of claim 17 which further includes means to adjust the stroke of said movable valve element, said stroke adjustment means being independent of said preload adjustment means.

19. A modular apparatus for ejecting a liquid from a pressurized source onto a substance, comprising a fixed service block module having essentially only static parts and defining a passage for liquid and a passage for pressurized operating fluid, said service block module having multiple apertures intersecting said passages,

a readily removable gun module mounted in each of said apertures of said service block module,

each of said gun modules including a nozzle,

means defining a fluid cylinder in each of said gun modules,

a piston in each of said fluid cylinders,

said gun modules including essentially all the movable parts of said apparatus and defining a first passage communicating between said liquid passage in said service block module and said nozzle and a second passage communicating between said fluid passage in said service block module and said fluid cylinder, said first and second passages of each of said gun modules being in sealing registration with their respective passages in said service block module when said modules are in assembled relation, and

a movable valve element in said gun module operatively connected to said piston for opening and closing liquid flow through said nozzle.

20. The modular apparatus of claim 19 in which each of said gun modules is generally cylindrical in configuration and in which said apertures are circular in cross section, said apertures having internal threads and said gun modules having external threads threaded into said threaded apertures so as to removably mount said gun modules in said apertures.

21. The modular apparatus of claim 19 which further includes spring means for biasing each of said valve elements of each of said gun modules to a closed position and adjustable preload means for adjusting the spring tension operable to maintain said valve elements in a closed position, said adjustable preload means enabling the several gun modules to be adjusted to equalize the pressure required to open each gun module.

22. The modular apparatus of claim 21 which further includes means to adjust the stroke of each of the movable valve elements of each of the gun modules, said stroke adjustment means being independent of said preload adjustment means in each of said gun modules.

23. The modular apparatus of claim 19 in which each of the said gun modules comprises a generally cylindrical b d havin a throu h ore extendin axial] therethr ugh, a %ortion of said body being eternall threaded so as to enable said body to be threaded into a threaded section of one of said apertures of said service block module, the axial bore of said cylindrical body being internally threaded at its opposite ends, said nozzle being threaded into said bore at one end, and a closure cap threaded into the threaded bore at the opposite end.

24. The modular apparatus of claim 23 in which a portion of said axial through bore of each of said bodies defines said fluid cylinder at one end of said cylindrical body and another portion of said axial bore defines a liquid chamber at the opposite end of said body, said first passage of said gun module communicating with each of said fluid cylinders and said second passage of said gun module communicating with said liquid chamber.

25. The modular apparatus of claim 24 which further includes spring means operable between each of said pistons and said closure caps to bias said pistons and said movable valve elements to a closed position.

26. The modular apparatus of claim 25 which further includes adjustable preload means for adjusting the spring tension operable to maintain each of said valve elements of each of said gun modules in a closed positron.

27. The modular apparatus of claim 26 which further includes means to adjust the stroke of said movable valve elements of each of said gun modules, said stroke adjustment means being independent of said preload adjustment means. 

1. A modular apparatus for emitting a liquid from a pressurized source onto a substrate comprising a service block module having essentially only static parts and defining a first passage for a liquid, and a second passage for a gun actuating pressurized fluid, said module having at least one aperture intersecting said passages, a readily removable gun module including a body mounted in said aperture of said service block module, said gun module including a nozzle, said gun module including essentially all the movable parts of said apparatus, said gun module body defining a first passage for liquid communicating between said liquid passage in said service block module and said nozzle, said first passage in said gun module body being in sealing registration with said liquid passage in said service block module when said modules are in assembled relation, said gun module body also defining a second passage for pressurized fluid communicating between said pressurized fluid passage in said service block module, said pressurized fluid passages of said gun module and service module also being in sealing registration when said modules are in assembled relation, a movable valve element in said gun module for opening and closing liquid flow through said nozzle, and movable means in said gun module responsive to connection with said pressurized fluid for operating said valve.
 2. The modular apparatus of claim 1 which further includes multiple apertures intersecting said service block module passages and a readily removable modular gun mounted in each of said apertures.
 3. The modular apparatus of claim 1 in which said gun module body is generally cylindrical in configuration and in which said aperture is circular in cross section, said aperture having internal threads and said gun module body having external threads threaded into said threaded aperture so as to removably mount said gun module in said aperture.
 4. The modular apparatus of claim 2 which further includes spring means for biasing each of said valve elements of each of said gun modules to a closed position and adjustable preload means for adjusting the spring tension operable to maintain said valve elements in a closed position, said adjustable preload means enabling the several gun modules to be adjusted to equalize the pressure required to open each gun module.
 5. The modular apparatus of claim 4 which further includes means to adjust the stroke of each of the movable valve elements of each of the gun modules, said stroke adjustment means being independent of said preload adjustment means in each of said gun modules.
 6. The modular apparatus of claim 1 in which the said gun module body is generally cylindrical body and has a through bore extending axially therethrough, a portion of said body being externally threaded so as to enable said body to be threaded into a threaded section of said aperture of said service block module, the axial bore of said cylindrical body being internally threaded at its opposite ends, said nozzle being threaded into said bore at one end and a closure cap threaded into the threaded bore at the opposite end.
 7. The modular apparatus of claim 6 in which a portion of said axial bore defines a fluid cylinder in said gun module at one end of said cylindrical body and another portion of said axial bore defines a liquid chamber at the opposite end of said body, said first passage of said gun module communicating with said fluid cylinder and said second passage of said gun module communicating with said liquid chamber.
 8. The modular apparatus of claim 7 in which said movable means includes a piston slideable in said cylinder and which further includes spring means operable betweEn said piston and said closure cap to bias said piston and said movable valve element to a closed position.
 9. A modular apparatus for ejecting a liquid from a pressurized source onto a substrate, comprising a fixed service block module having essentially only static parts and defining a passage for liquid and a passage for pressurized operating fluid, said service block module having at least one aperture intersecting said passages, a readily removable gun including a body removably mounted in said aperture of said service block module, said gun module including a nozzle, means defining a fluid cylinder in said gun module body, a piston in said fluid cylinder, said gun module body containing essentially all the movable parts of said apparatus and defining a first passage communicating between said liquid passage in said service block module and said nozzle and a second passage communicating between said fluid passage in said service block module and said fluid cylinder, said first and second passages of said body being in sealing registration with their respective passages in said service block module when said modules are in assembled relation, and a movable valve element in said gun module operatively connected to said piston for opening and closing liquid flow through said nozzle.
 10. The modular apparatus of claim 9 which further includes multiple apertures intersecting said service block passages and a readily removable modular gun mounted in each of said apertures.
 11. The modular apparatus of claim 9 in which said gun modules body is generally cylindrical in configuration and in which said aperture is circular in cross section, said aperture having internal threads and said gun module body having external threads threaded into said threaded aperture so as to removably mount said gun module body in said aperture.
 12. The modular apparatus of claim 10 which further includes spring means for biasing each of said valve elements of each of said gun modules to a closed position and adjustable preload means for adjusting the spring tension operable to maintain said valve elements in a closed position, said adjustable preload means enabling the several gun modules to be adjusted to equalize the pressure required to open each gun module.
 13. The modular apparatus of claim 12 which further includes means to adjust the stroke of each of the movable valve elements of each of the gun modules, said stroke adjustment means being independent of said preload adjustment means in each of said gun modules.
 14. The modular apparatus of claim 9 in which the said gun module body is generally cylindrical and has a through bore extending axially therethrough, a portion of said body being externally threaded so as to enable said body to be threaded into a threaded section of said aperture of said service block module, the axial bore of said cylindrical body being internally threaded at its opposite ends, said nozzle being threaded into said bore at one end and a closure cap threaded into the threaded bore at the opposite end.
 15. The modular apparatus of claim 14 in which a portion of said axial bore defines said fluid cylinder in said gun module at one end of said cylindrical body and another portion of said axial bore defines a liquid chamber at the opposite end of said body, said first passage of said gun module body communicating with said fluid cylinder and said second passage of said gun module body communicating with said liquid chamber.
 16. The modular apparatus of claim 15 which further includes spring means operable between said piston and said closure cap to bias said piston and said movable valve element to a closed position.
 17. The modular apparatus of claim 16 which further includes adjustable preload means for adjusting the spring tension operable to maintain said valve element in a closed position.
 18. The modular apparatus of claim 17 which further includes means to adjust the stroke of said movable valVe element, said stroke adjustment means being independent of said preload adjustment means.
 19. A modular apparatus for ejecting a liquid from a pressurized source onto a substance, comprising a fixed service block module having essentially only static parts and defining a passage for liquid and a passage for pressurized operating fluid, said service block module having multiple apertures intersecting said passages, a readily removable gun module mounted in each of said apertures of said service block module, each of said gun modules including a nozzle, means defining a fluid cylinder in each of said gun modules, a piston in each of said fluid cylinders, said gun modules including essentially all the movable parts of said apparatus and defining a first passage communicating between said liquid passage in said service block module and said nozzle and a second passage communicating between said fluid passage in said service block module and said fluid cylinder, said first and second passages of each of said gun modules being in sealing registration with their respective passages in said service block module when said modules are in assembled relation, and a movable valve element in said gun module operatively connected to said piston for opening and closing liquid flow through said nozzle.
 20. The modular apparatus of claim 19 in which each of said gun modules is generally cylindrical in configuration and in which said apertures are circular in cross section, said apertures having internal threads and said gun modules having external threads threaded into said threaded apertures so as to removably mount said gun modules in said apertures.
 21. The modular apparatus of claim 19 which further includes spring means for biasing each of said valve elements of each of said gun modules to a closed position and adjustable preload means for adjusting the spring tension operable to maintain said valve elements in a closed position, said adjustable preload means enabling the several gun modules to be adjusted to equalize the pressure required to open each gun module.
 22. The modular apparatus of claim 21 which further includes means to adjust the stroke of each of the movable valve elements of each of the gun modules, said stroke adjustment means being independent of said preload adjustment means in each of said gun modules.
 23. The modular apparatus of claim 19 in which each of the said gun modules comprises a generally cylindrical body having a through bore extending axially therethrough, a portion of said body being externally threaded so as to enable said body to be threaded into a threaded section of one of said apertures of said service block module, the axial bore of said cylindrical body being internally threaded at its opposite ends, said nozzle being threaded into said bore at one end, and a closure cap threaded into the threaded bore at the opposite end.
 24. The modular apparatus of claim 23 in which a portion of said axial through bore of each of said bodies defines said fluid cylinder at one end of said cylindrical body and another portion of said axial bore defines a liquid chamber at the opposite end of said body, said first passage of said gun module communicating with each of said fluid cylinders and said second passage of said gun module communicating with said liquid chamber.
 25. The modular apparatus of claim 24 which further includes spring means operable between each of said pistons and said closure caps to bias said pistons and said movable valve elements to a closed position.
 26. The modular apparatus of claim 25 which further includes adjustable preload means for adjusting the spring tension operable to maintain each of said valve elements of each of said gun modules in a closed position.
 27. The modular apparatus of claim 26 which further includes means to adjust the stroke of said movable valve elements of each of said gun modules, said stroke adjustment means being independent of said preload adjustMent means. 